Espresso Dose and Yield Calculator: Basket, Flow and Fix
An 18 gram basket takes a 17 to 19 gram dose, yielding 34 to 38 grams at a 1:2 ratio in 25 to 30 seconds. That is a flow rate of about 1.3 grams per second. Above roughly 2 g/s the shot is running too fast and needs a finer grind, below roughly 1 g/s it is too restricted and needs a coarser one.
Espresso is three numbers: dose in, yield out and time. This works out the dose your basket wants, the yield your ratio implies, and the flow rate your shot actually ran at, then tells you the one thing to change. Weigh both ends with a 0.1 g scale , because volume in a cup is mostly crema.
An 18 g basket takes a 17.0 to 19.0 g dose.
An 18 g dose yielding 36 g in 27 seconds is a textbook 1:2 double at about 1.33 g/s.
Guidance only, and taste always overrules a calculator. These windows are conventional starting points, not rules.
What dose belongs in your basket?
A basket's gram rating is a centre point, not a maximum. An 18 g basket is designed so that 18 g of ground coffee at a normal roast density fills it to the correct depth, leaving the right headspace between the tamped puck and the shower screen once the portafilter is locked in. The usable range is roughly plus or minus one gram either side.
| Basket | Dose range | Yield at 1:2 | Typical time | What it is for |
|---|---|---|---|---|
| 7 g single | 6.5 to 7.5 g | 13 to 15 g | 20 to 26 s | Rarely used at home, hard to prep evenly |
| 14 g double | 13 to 15 g | 26 to 30 g | 25 to 30 s | Older machines and some 51 mm baskets |
| 15 g double | 14 to 16 g | 28 to 32 g | 25 to 30 s | Common stock basket on 54 mm machines |
| 18 g double | 17 to 19 g | 34 to 38 g | 25 to 30 s | The modern reference for a double |
| 20 g double | 19 to 21 g | 38 to 42 g | 26 to 32 s | Bigger drinks, milk-heavy recipes |
| 22 g triple | 21 to 23 g | 42 to 46 g | 28 to 34 s | Needs a deep basket and a taller group gap |
Two practical notes the table cannot carry. Very light roasts are denser than dark ones, so the same 18 g occupies less volume and leaves more headspace, which is one reason light roasts often behave differently in the same basket. And stock baskets are frequently rated optimistically: a basket sold as 18 g on a budget machine is often closer to 15 g in practice, which is one of several reasons a precision basket is a worthwhile early purchase.
What does flow rate tell you that time does not?
Flow rate is yield divided by time, in grams per second. It is more useful than time alone because it is independent of the size of the drink. A 36 g yield in 27 seconds and a 54 g yield in 40 seconds are both about 1.33 g/s, which means the puck was offering the same resistance even though the shots look very different.
| Flow rate | g/s | What it usually means | The single change |
|---|---|---|---|
| Gushing | above 2.5 | Water is barely meeting resistance, often a channel or a badly under-dosed basket | Grind much finer, and check the dose |
| Fast | 1.8 to 2.5 | Under-extracted, reads sour and thin | Grind finer, one step |
| In window | 1.0 to 1.8 | Conventional range for a 1:2 double | Nothing. Judge by taste |
| Slow | 0.6 to 1.0 | Over-extracted, reads bitter and drying | Grind coarser, one step |
| Choking | below 0.6 | The bed is too restrictive, or the dose is well over basket spec | Grind much coarser, and check the dose |
A scale that reports live flow rate, such as the BOOKOO Coffee Scale with Timer and Flow Rate , shows this while the shot is still running rather than afterwards. That matters because channelling has a signature: flow accelerates sharply mid-shot as water finds a path. On a standard scale you only discover that from the taste.
Why change grind rather than dose?
Because they fix different things. Grind size changes how hard it is for water to get through the bed, which is exactly the fault when a shot runs fast or slow. Dose changes how much coffee is in the basket, which changes strength and headspace and only moves flow rate as a side effect.
Raising the dose does slow a shot, and it is a legitimate lever once you know what you are doing. The problem with using it as a repair is that you have now changed the drink as well as the flow, so you cannot tell which change caused the difference in taste. Adjust one variable at a time, and let grind be the one that moves.
There is one exception worth knowing. If your grinder has coarse steps and you are stuck between two settings, one too fast and one too slow, then a small dose change is the correct fine adjustment. That is a symptom of a stepped grinder rather than of technique, and it is a large part of why stepless grinders exist. The grinder guide covers the difference.
What if the numbers are right and it still tastes wrong?
Then the problem is upstream of the recipe, and it is almost always one of four things.
- Distribution. Clumps from the grinder create low-resistance paths before you even tamp. A needle distribution tool is the largest measurable improvement per dollar in espresso.
- Tamp. A tilted tamp means one side of the bed is denser than the other, and water takes the easy side. A calibrated tamper removes pressure and angle as variables.
- Temperature. A machine that has not warmed through, or one without PID cycling several degrees, will read differently shot to shot at identical numbers.
- Bean age. Espresso wants beans roughly 7 to 21 days off roast. Fresher than that and carbon dioxide disrupts the bed, older than that and the coffee is flat.
The symptom-to-fix mapping for all of these is in the extraction troubleshooting chart, and the physical technique is in the puck prep guide.
How does this fit with the rest of the dial-in?
Use the brew ratio calculator to decide what drink you are making, use this tool to check whether the shot you pulled matched it, and use the brew ratio chart when you want a full lookup rather than a single answer. The whole sequence from a new bag to a repeatable shot is in how to dial in espresso.
If the grinder is what is holding you back, and it usually is, the espresso grinder roundup covers what actually changes when you move up. A grinder like the Baratza Encore ESP Coffee Grinder is the entry point at which espresso adjustment becomes possible at all, and the tiers above it buy resolution rather than a different kind of coffee.
Frequently asked questions
What dose should go in an 18 gram basket?
Between about 17 and 19 grams. A basket rated 18 g is designed around that mass of ground coffee at a normal roast density, and the rating is a centre point rather than a maximum. Going more than about a gram over reduces headspace, so the puck swells into the shower screen and the bed cannot expand evenly. Going more than a gram under leaves the puck too thin and it fractures under pressure.
How do I know if my espresso shot was too fast?
Compare flow rate rather than time alone. A conventional 1:2 double at 18 grams in and 36 grams out over 27 seconds is about 1.3 grams per second. Much above 2 grams per second means the water is getting through too easily, which usually reads sour and thin. Much below 1 gram per second means the bed is too restrictive, which usually reads bitter and drying. Grind is the lever for both.
Should I change dose or grind to fix a fast shot?
Grind, in almost every case. Dose changes the amount of coffee and therefore the strength and the headspace, and it moves flow rate only as a side effect. Grind changes flow rate directly, which is the actual fault. Raising dose to slow a shot works, and it also changes the drink you are making, so it should be a deliberate recipe decision rather than a repair.
What is headspace and why does it matter?
Headspace is the gap between the tamped puck and the shower screen once the portafilter is locked in. It has to exist, because a wet puck swells during the shot. Too little and the puck presses into the screen, which stops the bed expanding evenly and leaves a screen imprint. Too much and water pools above the puck before it engages. Both show up as inconsistency rather than as an obvious fault.
Does a bigger dose make a stronger espresso?
It makes a more concentrated one if you keep the yield the same, because you are dissolving more coffee into the same amount of liquid. If you scale the yield with the dose to keep the ratio fixed, strength stays roughly constant and you simply get a larger drink. That is the practical difference between changing dose and changing ratio, and it is why the two should be adjusted for different reasons.
Why does my shot time change when I change nothing?
Usually one of three things: the grinder is retaining grounds from the previous setting, the machine has not fully warmed up, or the puck preparation varied. Retention is the most common on grinders that hold coffee between the burrs and the exit, because the first few grams out are ground at the old setting. Purging a gram before dosing removes that variable entirely.
How we choose: we compare published manufacturer specifications, verified owner reviews and published barista guidance. We do not test gear in person. Espresso machines run mains electricity, pressurised water and steam above boiling point, so follow your manufacturer's manual and leave electrical or boiler work to a qualified technician. Everything here is researched guidance, not professional advice.